The fastest mechanical launcher?

[nature-boy]

As boyntonstu opened the thread, I immediately searched for the book and found the same what JSR said (you don't have to read trough the text, the sub-title of the book already says: "...Blowpipes, Big Airguns,..."),
but I don't think that is what boyntonstu is looking for. If he wanted "pneumatic, high pressure, hand pumped rifle" as an answer, he wouldn't open a thread on this site...
Or he should have known better....